Methods for assessing responsiveness: a critical review and recommendations

A review of the literature suggests there are two major aspects of responsi veness. We define the first as "internal responsiveness," which characteriz es the ability of a measure to change over a prespecified time frame, and t he second as "external responsiveness," which reflects the extent to which change in a measure relates to corresponding change in a reference measure of clinical or health status. The properties and interpretation of commonly used internal and external responsiveness statistics are examined. It is f rom the interpretation point of view that external responsiveness statistic s are considered particularly attractive. The usefulness of regression mode ls for assessing external responsiveness is also highlighted. (C) 2000 Else vier Science Inc. All rights reserved.